Scientific and Useful.

Bruce Herald, Volume XVII, Issue 1623, 27 February 1885, Page 6

Scientific and Useful.

♦ If kept for a lorg timo, zinc-white bocomes granular and gritty, and u-cless for painting ; it may bo restored by ignition in an carlliern cruciblo. UTILISING NIAGARA.. It is stated that conic tentntivo experiments in utilising Niagara for tho production of powor to bo transmitted by electrical means havo been made. A generator bus been placed in Lbo papor mills at Niagara Falls, and tlio mucliino connected with 20 miles of wire, with a successful '"esult — though what that is we do not know. GELATINE DYNAMITE. Experiments with gelatine dynamite have doveloped interesting results. Tho test is made by enclosing the compound in a cavity of lead with very thick walls. By exploding 30 grammes of No 1 golafine dynamite in a cavity whoso capacity wus 15 cubic centimeters, tho spucc was enlarged to 1330 cubic centimeters, nearly in tho ratio of one to ninety. ELKCTEIC POWER. The first experiment on tho New York railways with oloctricity as a motivo power will, it seems, bo made on the Second Avonuo line. A central rail, 201 b hoavier than those at present in use, will bo laid between tho metals extending ; from Chatham Square to the Harlem River terminus. Tho central rail will bo insulated, and tho current from tho generators will be conducted to it by a copper rod. A commission seloctod by the companies interested will decide which is tho beet of the inventions submitted to experiment. SOFT AND HARD COAIj. In general soft cool runs higher in heating power than hard coal, on account of the higher percentage of available hydrogen, and yot, notwithstanding this fact, it very often happens tlat un anthracite coal yields more heat than a bituminous. This may occur when tho carbon is very high, and tho percentage of ash is very small. But tbo larger per ccntago of hydrogen in bituminous coals renders them the great producers, while their relatively lower market value is an additional incentive for their purchase by large factories. THE SENSES OF BEES. Experiments conducted by Sir John Lubbock eoera to show that bees have a preference for bluo flowers. Beside this curious display of a colour sense, there is some reason to believe that these * bu°y ' insects may possibly possess in a very rude state tho power of hearing. Some bees were trained to come for honey placed on a musical box, on the lawu closo to a -window of the houso. Tho bos was made to play several hours daily for a fortnight ; it was then brought indoors out of sight, but close to the open window, about seven yards from its former position. The Dees did not, however, find the honey, though when it was once shown to them thoy camo promptly enough.— Little Folks. SNOW WATER IMPURITIES, Under tho heading of ' The Beautiful Snow," tho Mioroscope points out tho kind of organic impurities found in snow, which, added to what wo recently quoted on the same subject, very conclusively bliows the fallacy of tho idea that molted snow forms a good substitute for distilled water. Tho impurities are as follows : — Living infusoria and algso, bacilli and micrococi, mites, diatomß, add great numbers of fungi spores also fibres of wood, mouse hairs, pieces of buttorfly wings, skin of larvro of ineocts, cotton fibres, pieces of grass, epidermis, pollen grains, rye and potato flour, grains of quartz, minute pieces of roofiug tile, and bits of iron and coal. TIIE SUN. Recently a very interesting lecture was given by Mr Win. T, a nt Carpenter, 8.A., B,Sc, JT.C.tf., on ' The Sun.' Beginning by throwing on a screen a diagram, in whicn, by a mechanical contrivance, tho planets were Been revolving round the sun. Tho lecturer explained tho impossibility of making astronomical diagrams to scale, on account of tho enormouß distances involved. Tho sizo of tho oarth is to that of tho sun as a pea to a globo two foot in diameter or, to put it in another way, thirty eartbs placed side by sido would about reach to the moon ; yot if the sun were hollow, there would bo more than room inside it for the moon to revolve round the earth. As to the distance of the sun from the earth, a baby, starting in an oxpre»B traia, travelling a mile a minute would oe 99 years old before he had gone halt way. Or, imagine a baby with an arm long enough to touch the sun, ho would be 100 years old before ho felt the consequent burn ; for tho rate at which sensation passes along tho nerves to tho brain is known, and it woulc! take 100 years to pass over tho distance between tho sun and earth at that rate. After describing solar eclipses, tho lecturer went on to solar spot?, more plentiful at intervals of 11 years apart, aod more scarce half way between those times. When Bpots are plentiful in tho sun, so also are cycloneß in the Indian Ocean, tho rainfall is greatest over the whole oarth, auroras uro numerous, and magnetic disturbances greatest. the velocity: of tub moon. We can faintly picture, perhaps, how it would seem, from a station near tho lunar orbit, to see the moon — a moving worldrush by with v velocity greater than that of tho cannon ball in its swiftest flight; but with equal speed its shadow actually travels along tho eurch ; and now, if wo return from our imaginary station to a real one hero below, we are better prepared to Bee why this flying shadow is such a unique sqectaulo ; for, small as it may be when seen in relation to tho whole globe, it is immense to the observer, whose entiro horizon is filled with it, and who sees the actual velocity of one of the heavenly bodies, as it wore, brought down to him. Tho reader who has over aecoudod to tho Suporga, at Turin, will recall tho maguificont view, and bo able to understand tho good fortune of an observer (Forbes) who once had the good fortuno to witness thonco this phenomenon, and under a nearly cloudless sky. " I perceived," he says, "in tho southwest a black shadow like that of a storm about to break, wnioh obscured tho Alps. It was the lunar shadow coming towards us." And ho speako of tho "stupolaction" — it ib his word — caused by the spectacle. " I confess," ho continues, "it was the most terrifying sight I ever saw. As always happens in tho cases of sudden, silent, unexpected movements, tho spectator confounds real and relative motion. I felt almost giddy for a moment, as though tho massivo building under me bowed on tho sido of tho coming eclipse." Another witness, who had boon looking at some bright clouds before, says : — " Tho bright cloud 1 distinctly caw put out like a candle. Tho rapidity of tho shadow, and the intensity, produced » fooling that oomething matorial was sweeping over the earth at a speed perfectly frightful. I involuntarily listened for tho rushing noise of a mighty wind."— Professor Langley, in the Century,